1. Department of Computer Science and Information Engineering, Asia University, Taichung 41354, Taiwan. (e-mail: dodinhthuan@tdtu.edu.vn)
2. Faculty of Electronics Technology, Industrial University of Ho Chi Minh City (IUH), Ho Chi Minh City 700000, Vietnam.
3. Department of Telecommunications, VSB Technical University of Ostrava, 70833 Ostrava, Czech Republic.
4. Department of Computer Engineering, Rochester Institute of Technology, Rochester, NY, 14623, USA.
5. Computer Science Department, Federal University of Ceara, Fortaleza 60440-900, Brazil.